Fix ResizeFormListener using integer keys

When using CollectionType, the data is an array with integer keys
and the expected type is FormInterface|string.

src/EventListener/ResizeFormListener.php

@@ -105,6 +105,8 @@ public function preSetData(FormEvent $event): void
                 'data' => $value,
             ]);
 
+            $name = \is_int($name) ? (string) $name : $name;
+
             $form->add($name, $this->type, $options);
         }
     }

tests/EventListener/ResizeFormListenerTest.php

@@ -53,6 +53,27 @@ public function testPreSetDataWithNullData(): void
         $listener->preSetData($event);
     }
 
+    public function testPreSetDataWithArrayData(): void
+    {
+        $listener = new ResizeFormListener('form', [], false, null);
+
+        $form = $this->createMock(Form::class);
+        $form
+            ->method('getIterator')
+            ->willReturn(new \ArrayIterator());
+        $form
+            ->expects(static::exactly(2))
+            ->method('add')
+            ->withConsecutive(
+                ['0'],
+                ['1'],
+            );
+
+        $event = new FormEvent($form, ['foo', 'bar']);
+
+        $listener->preSetData($event);
+    }
+
     public function testPreSetDataThrowsExceptionWithStringEventData(): void
     {
         $listener = new ResizeFormListener('form', [], false, null);